All this matters because, until Underworld, Bjork and the Prodigy, the reason dance music didn't make it into the national pop buyer's consciousness was that it had no stars. No matter how awe-inspiringly phat the beats are, the reality is all too often just two bald blokes and their computers. Underworld pick up where the multi-coloured Keith Prodigy left off. Darren and Rick's computers are programmed with every single sound Underworld have ever recorded in the studio. Live, they bring these noises in and out when they choose, creating an improvised "wall of sound" for Karl to play with. And how. He climbs the speakers, dances with more energy and wild-eyed desperation than Jennifer Beals in Flashdance and occasionally calms down long enough to strap on a guitar and sing.
"It's emotionally exhausting trying to tap into the crowd's subconscious while trying to remember which way is up," says Karl.
"Born Slippy", taken from the Trainspotting soundtrack, is the song that has dominated the Top 10 for weeks and captures the essence d'Underworld: stream of consciousness lyrics ("shouting lager lager lager lager!/ random blonde boy/ going back to Romford/ on my way to a new age tension headache") that if you read too much into them, could explain everything that's wrong with leaving the house. It has huge, anthemic beats, and is stupidly catchy for a song with, basically, no tune. The week before its release, Radio 1 played it twice in 10 minutes. It is an astonishing single, especially in its celluloid context: Renton bounding into the sunset to start a new life. If "Firestarter" was dance Sex Pistols then "Born Slippy" is techno Springsteen.
In conversation, Karl is twitchy and wired, one ear perpetually cocked to the pub TV screen and the office workers' lunch-break chat - this is where he gets most of his lyrics from. Born in Worcestershire, he lived in Cardiff for eight years, which is where he met Rick. Dreaming of pop stardom, they moved to ... Bexhill-on-Sea. "We went there because it was somewhere other than Cardiff." But Karl, a lot of places aren't Cardiff. "And that was one of them." The original Underworld were nothing like the dance innovators of today. For more than 10 years, Rick and Karl comprised a funk-pop band called "Freur" who supported the Eurythmics on their last American tour and had a number one hit in Italy with a single called "Doot Doot". A week before they were dropped by their label, they decided to drop themselves.
"We were obsessed with Kraftwerk and dub music, yet we were stuck, in the middle of a tour, with a style we realised wasn't something we were interested in anymore. Re-inventing yourself in the music business is anathema to most people - apart from the real innovators like Miles Davis or Frank Zappa. Most musicians are encouraged to stay the way they are."
Inspired by Acid House, they started again from scratch. Through mutual friends, they persuaded hot- shot DJ Darren Emerson to work with them, and the full Underworld line-up recorded their first track as "Lemon Interrupt". Darren was a hip hop-Balearic -electro freak who took a job on the stock exchange and then followed his heart into full-time DJ-ing. Whereas Rick and Karl are classic deep-thinking Celts, Darren calls all women "love" and "darling" until he gets so drunk that he calls all the blokes "darling" too. The personalities mesh well; their neuroses fit together, if you will. The debut album, DubNoBassWithMyHeadMan, yielded the classic techno anthem "Rez", and offered stranger, less danceable, more mind-bending tunes, such as the JJ Cale-esque "River of Bass". "Second Toughest..." is more Jungle rooted, breathless and relentless. And more Mercury nominated.
"We won't win," laughs Darren, "but I'm really chuffed about it, anyway. I just think, we done all right, lads." A European journalist recently asked Darren, "What's it like working with two old blokes?" Well?
"I never wanted to be a pop star. They both did, for 15 years. The success of 'Born Slippy' has brought too much touring for my liking. I'm just desperate to get back into the studio."
Karl is worried that "Born Slippy", with its "lager lager lager" refrain, has been misinterpreted as a beer-boy anthem: "It was supposed to be ironic."
Darren snorts contemptuously. "You can't change that, so I don't give a shit about it. Karl's different from me. I don't care. I just think you've got to go with it and live with it. If people want it to be a lager anthem, great."
If it is a lager anthem, then at least dance music is no longer purely synonymous with drug use, specifically Ecstasy. Karl has never taken a single drug in his life.
"My behaviour on stage and in front of the camera might suggest drug use. But nope, it's just not my thing." His press officer interrupts, "I'm sorry, can you imagine Karl on drugs?" Karl nods his head, almost sadly. "As things are now, I'd like someone to tell me where the planet is."
This weekend, Underworld headline the second stage at Reading. They are on at the same time as the Stone Roses. It is ironic, as Alanis Morissette would no doubt point out, that the once great Roses are now at their lowest point, with a new guitarist who plays a solo with his teeth. And Underworld are at the height of their powers, a dance band so inventive and compelling that they make guitar music seem redundant - all the more powerful since a large part of the stage show features Karl on guitar. It's what we have come to know as "Pulp syndrome": Underworld are the greatest 15-year overnight successes in pop.
n Underworld play the Reading festival on SundayReuse content